The present invention relates to a canister using adsorbing material or adsorbent such as activated carbon and especially to a canister usable for treatment of fuel vapor of an internal combustion engine of a vehicle, for example. Furthermore, the present invention relates to heat storing material usable in a canister, and method for producing the heat storing material and/or a canister using the heat storing material.
In a system of an internal combustion engine for a vehicle, for example, there is generally provided a canister capable of adsorbing and releasing fuel vapor produced by evaporation in a fuel tank, in order to prevent emission of fuel vapor into the atmosphere. The canister is arranged to trap or adsorb fuel vapor generated, for example, in the stop state of a vehicle, and to purge or release the trapped fuel vapor with fresh air, for combustion disposal in the internal combustion engine during operation of the engine. In the case of adsorption in a canister utilizing an adsorbing material such as activated carbon, the temperature in the canister becomes higher because of exothermic reaction, and the temperature increase tends to deteriorate the adsorbing performance. In the case of desorption of fuel vapor, on the other hand, the reaction is endothermic, and the temperature becomes lower so that the desorbing performance becomes poorer.
To meet this problem, a patent document 1, US 2001/0015134 A1 (≈JP 2001-248504 A≈EP 1 113 163A2)) proposes a fuel vapor treatment canister including a vapor adsorption chamber which is formed on a fuel vapor inlet/outlet side and which contains a vapor adsorbing material, and a heat accumulation and vapor adsorption chamber which is formed on an air inlet side of the canister casing and which contains a heat storing (or heat accumulating) material as well as the adsorbing material.
To meet the above-mentioned problem, a patent document 2, US 2005/0247202 A1 (≈WO2003/106833≈EP 1 536 128 A), and a patent document 3, US 2005/0188851 A1 (≈JP 2005-233106≈EP 1 566 535 A) propose technique of restraining temperature change due to adsorption and desorption and improving adsorbing and desorbing ability by filling the inside of a canister with not only an adsorbing material but also a heat storing material formed into a granular form by adding a binder to micro capsules each enclosing a phase-change material for absorbing latent heat and releasing heat with phase change.